The growth of telecommunications systems satisfying mobile communication problems has led carriers and the industry to develop and use base stations that are increasingly complex. At present, constraints related to the number of sites in operation are making it increasingly difficult to continue installing new antennas indefinitely, and it is therefore becoming necessary to use wideband antennas instead of a plurality of single-band antennas or to use the same antenna to cover a plurality of separate areas.
In the field of mobile telephones, cellular coverage may be obtained from single-beam/multibeam antennas whose radiation areas are made adjustable in direction and in angular width by using active elements that control the feed to planar array antennas or focal array reflector antennas for sighting angles of ±30° to ±40°, or are disposed on a cylindrical surface so as to be able to point one or more beams over 360°. There is a direct relationship between the complexity of the feed array and the capabilities and the agility of the antenna, and the complexity increases even faster when forming multiple independent beams. The set of beams must be managed via active radio frequency amplifier, phase shifter, and delay line components operating in the frequency bands of the antenna. These components drastically increase the cost of the antenna or limit its capabilities, if a reasonable cost is to be obtained (for narrow band use, etc.). Moreover, the feeding losses of such active printed array antennas are not negligible and may limit their intrinsic performance.